Friday, March 25, 2011

I Drink the Beer I Make

Time and temperature are two important parameters that are monitored during the brewing process. I developed a device that times the various brewing steps and where applicable monitors the temperature.

Here is a list of the available functions:

Brew – Starts a timer showing time for the overall brewing process. It also displays the current battery voltage and display a warning if the voltage is getting low.

Strike – Displays the temperature as the strike water is heated. It also displays the temperature rate of change so the end time can be predicted.

Mash – Tracks the time and temperature during the mashing process. A warning will be displayed and an alarm sounded if the temperature falls outside the minimum and maximum allowed range.

Sparge – Similar to the mashing function.

Boil – Tracks the time during the boiling process. An alarm is sounded for each of the hop additions.

Chill – Monitors the wort temperature as it is cooled and sounds an alarm when it reaches the desired temperature.

Alarm Toggle – This will enable or disable the alarm sound.

Display Backlight – This will turn on or turn off the display backlight.

Defaults – These are the tunable parameters such as minimum temperature and maximum temperature, mash, sparge and boil times, etc.

I used the Pololu SVP-324 for the hardware platform. The SVP makes a good general purpose project platform. The SVP has all of the needed hardware for this project except the temperature probe.

Here is a list of the hardware functions I used. There are many more features available such as motor controllers, multiple digital inputs and outputs, servo control lines and two regulated power supplies one of which is adjustable.

ATmega324PA AVR microcontroller (32 KB flash,2 KB RAM, 1 KB EEPROM)

16x2 LCD display with backlight

Three Buttons

Buzzer

One of the eight analog inputs

The temperature probe was constructed using a two foot long piece of copper tubing and a TMP36 temperature sensor. The copper tubing is the type used to run a water line to a refrigerator ice maker. The TMP36 fits perfectly inside the tube.

The steps to make the temperature probe:

·Straighten the desired length of copper tubing.

·Crimp one end and seal it with a non-lead based solder.

·Use heat shrink tubing for each lead to insulate each lead soldered to the each of the three wires.

·Insert the sensor and wire into the open end of the tube until it hits the bottom.

·Seal the opened end with silicon sealant. This end should not be submersed in the liquid.

·Wrap this end with a thermal insulation material such as foam or vinyl tubing so the probe can be handled safely when removing it from a hot liquid.

At some point I will decide on a water resistant case for my BrewMon project. For now I am just using a plastic baggie.